A/f How can it be

[Kahler]

I have a good one, I think. As I been told Trinity does not read A/F accuratly beacuse it getting the reading from the factory A/F sensor. Our 5.7 chally have 4 #, Two on each side one in the upper portion of the cat. and other 10in. out of the ex. manifold. I installed a bosh wide band A/F sensor and meter inbetween the two. I logged with the Trinity, and at the same time made notes of my A/F wideband gauge. Trinity is reading exactly as my wide band reads A/F Exactly the same numbers at the exact same time.
Its no problem, I wanted to know why.??
Im told the trinity was not supposed to read the accurate A/F numbers ?
Mine reads exactly the same ? wot 11.5 Trinity, 11.5 Wideband ?
Is somthing diffrent with the Trinity, or are the 5.7s getting a more accurate narrowband ? I dunno,, anyone got some light on this ?
Anyone haveing the same luck as I Thanks

[duster360]

The short answer to your question Why? -->>Your car's engine isn't modified enough to change the amount of air flow the PCM is expecting.

The A/F shown in the logs as the PID "Open Loop F/A" is the PCMs commanded A/F. Its the A/F the PCM would like to have if the airflow entering the engine matches its programming. During WOT there is not any feed back to the PCM so it can change its fueling. The amount of air the PCM is programmed to expect is somewhat fixed unless its changed be a CMR tuner.

So if the engine is modified in certain respects, it can inhale a little more(hopefully) or unfortunately a little less than what the PCM is expecting and the Open Loop FA will vary from the the measured A/F from a wideband.

[Kahler]

Wow, I dunno, got lost there sorry. I just thought the Trinity reading from the factory sensors was not accurate, this by by DS own information. So cool ok, As I checked it with a stand alone wideband sensor and meter just to see the real A/F with seperate wideband, walla. Trinity reading and logging exactly the same as the wideband a/f meter i installed as a stand alone. ? ??????
I respect your answer duster 360 and help, thats cool I just not understandin ?/?%#$@ duhh. where am I missing.?
Help me understand

[Quick]

You're both saying the same thing.

The stock sensors are narrowband A/F sensors. They have a *very* narrow range they operate in that's calibrated for 14.7:1. Outside of that they are only good for reading "rich" or "lean" and not how much rich or lean. So... when the PCM reports A/F it's a modeled (calculated) number and not a direct reading. The PCM does not use the stock (narrowband) sensors to report A/F. The PCM uses a bunch of parameters in the calculation (timing, temps, injector pulse widths, etc, etc,)as well as some known constants. Those "known" constants are based on the stock (mainly physical) engine. flow rates, injector sizes, volumetric efficiency, stock intake, stock exhaust, etc. etc.

The calculation is pretty accurate on a stock engine. But... it is calculated and not an actual reading. As you modify a car with (maybe) CAI, exhaust and (certainly) long tubes, heads, cams, etc it will be further off from actual.

What Duster is saying is that your car is stock enough that you would expect the calculated number to be close to actual.

[duster360]

I should have been more clear about the factory O2 sensors. Quick's right. The A/F displayed on the Trinity has absolutely NOTHING to do with the factory O2 sensors. All of your vehicals O2 sensors ouputs are ignored during WOT. Thats why the A/f displayed is called Open Loop FA.

The term 'Open Loop' means there is no A/F control feedback from the O2 sensors what so ever. Conversly, CLOSED LOOP(idle, cruise) uses the O2 sensors to adjust A/F close to 14.7:1.

Again; since WOT is Open Loop, the PCM's target A/F(Pid: OpenLoop FA) can vary from the actual A/F as measured by the wideband.

[Kahler]

Yeee ha thanks alot felers, I now see, said the blind man. lol lol Thanks, I now can wrap this around my head. So what does give the pcm, at wot the open loop the a/f of 11.7 it it as you said ALL the other readings combined, right. So when we add fuel with the Triinity 2% 8% or what ever we set it at, whats being changed,,,, more/bigger, opening of the injsctors and longer bandwith for more fuel ??, And if now, at wot and I have say 11.7, and I add say 20% will or should I see my wideband a/f gauge go down in numbers, say to maybe 11.2 or somthing ? I am just trying to learn all I can. And thanks for the help quick and duster 360

[duster360]

A 20% Fuel change will be F'en RICH! 11.77 + 20% = 9.4:1 as shown as the PID Open loop FA. Your widband will be close to this but might be a little off.(NEVER go below 11.0:1, as reported on the wideband, for any reason)

Knowing the correlation between OLFA and true A/F can be quite handy in tuning and diagnosis of fuel problems

If, for example, your pump is weak or your injectors are maxing out, the OLFA could be 11:1 but the wideband might only read 12.0. If you were in this case to add 20% to drop OLFA to 8.8:1, BUT wideband WOT A/F stays at 12.0 or drops only slightly, then there's a good chance you have a fuel system issue(weak pump or injectors that are too small)

When ever OLFA differs from measured wideband FA a change in either Airflow or fuel flow has occured

[Kahler]

I see again, And thanks for the information. I was using the extream just for example is all. My understanding is much better.
When I decide to hook up my sensor to the Trinity with the jack plug. Will the trinity find, or have a pid for the wideband will it be plug and play for recording data logging ? F/a Thanks

[duster360]

No you have to set up the analog's units and MIN/MAX voltage.
For my wide band I set 0v = 8A/F and 5v=20A/F,,or something like that.
Then you need to add it as a "Gauge" in your layout just as you would if you're adding a PID.

[Kahler]

Humm, ok now I know, thats not going to be plug and play,,,lol, My gauge is a EIG gauge / and bosh wideband sensor set up. The sensor at the exhaust, going to the gauge and from my gauge I have 2 extra wires provided for data logging that has a set voltage 0 to 5 vdc I think to and from the sensor in coralation with the a/f gauge. In the directions it shows how to hook to a jack. My question is there a setting in the trinity to get and adjust to get it to read proper A/f as the gauge shows to put each other in scync with each other ? the signal from the gauge ( 0 to 5 v ) as the Trinity should read and the give reading of the A/F ? right, and, or, how. ? Thanks

[gizmodo]

That is what duster is saying above. Basically, you tell the Trinity the lowest and highest value it will see, and what AFR that correlates to. So, in Duster's example 0 volts means the AFR is 8, and 5 volts means the AFR is 20. The Trinity assumes the output is linear, so it is able to calculate the values based on what you supplied. It will read in AFR. You just have to figure out what the min and max voltages and values are and you will be all set. You should be able to get that info from the manufacturer of your wideband.

[Kahler]

Ya,,, baby. iv gotten tuned in now. My Trinity matches my wideband. Excellent and thanks to all.

[4drturbo85]

Old thread quick question.

My wideband gauge (Innovate LC2) shows 11.2ish AFR @ WOT from 3-6k. But my logs are saying 12.2 AFR. Go by the AFR gauge correct?